Within the last three months I've added two snails to my betta fish's tank. They seem to be getting along well other than the occasional flaring (Fish -- yes, that's his name -- doesn't seem to like the color orange for some reason), but about a week ago I noticed a little spot on the crown of my snail's shell. It seems to be growing some. I took pictures, can anybody identify if this is dangerous or just part of the growing process?